Toxicology is a modern science. Because of the rapid development of industry and agriculture, the amount of chemicals increases explosively. There has been more than 26,000,000 chemicals registered in the world and over 2000 new chemicals are produced every year. Therefore the traditional methods of toxicological evaluation cannot meet the requirements in the modern society, let alone the precise toxicological study for various chemicals. It is needed to make innovation in theory, so as to shorten the period, reduce the expenditure and input in the research, which may make the applications of chemicals safer. Meanwhile, as animal welfare is putting on the public agenda, less animals will be permitted to be used largely in the toxicological research. All of these promote the development of theoretical toxicology.